Thermoquad question

OK, after a vacation camping trip with wife and dogs, I am back on this.

I enriched the rods screw a bit. The slight stumble when cracking throttle seems to be gone for now. The part throttle reading of 10's A/F is gone.
But I still have some really weird stuff going on!!!

I get a good A/F reading for a bit, 14.5 idle and had cruise at 15 A/F, 12's WOT from cruise, WOT from standstill goes 10.X then climbs to 11's/12. All this is really fine. ...But then, I blip the throttle or accelerate and the reading goes really lean. (17 to off scale.)
I've had several incidents of this. I get the tuning good, then all of a sudden I'm lean, then OK. It runs fine through all this. Plugs are perfect. Just went for a warmed up neighborhood drive and it's back to "off the scale" lean to richest of 17+!!i!

Could this be an O2 sensor failing, or the meter??